The present invention relates in general to prefabricated wall units, and, more particularly, to prefabricated wall units which are coupled together.
Conservation of energy has always been a concern in the building construction industry, and wall units such as that system disclosed in Callahan, U.S. Pat. No. 3,048,244, have been widely used. While systems such as that disclosed in the Callahan, et al. Patent produce relatively good thermal performance, that thermal performance has been found somewhat deficient in light of the new and more demanding energy conservation requirements which are now being used by the building industry.
The thermal performance of the Callahan, et al. system is limited because of the thermal conductance characteristics at the joints used to connect the wall panel units together. Accordingly, if the thermal resistance of the wall panel joints of the current systems, such as that disclosed in the Callahan, et al. Patent, can be improved, such systems can be used in the construction of buildings and still have those buildings meet, or exceed, the new energy conservation requirements used in the building industry.
Some prior art devices have compressible edge seals, but such seals are not true thermal breaks but are for other purposes, such as ease of construction only. Thus, considerable heat loss occurs at panel joints. Other prior art devices merely interpose gaskets and the like to reduce air infiltration, but again, some devices do not have true thermal breaks. In fact, there may even be contact between heat conducting elements in such devices thereby producing a heat path through the panel joint.
In all the prior art devices, the elements used in the panel joint are now proving to be inadequate to properly reduce heat flow through the assembly.
Rather than having elements composed of a single thin member which is not a true thermal break, the device embodying the teachings of the present invention separates the inner and outer panel faces to a considerable distance, thereby producing a true thermal break in the sense that the heat path is interrupted sufficiently to satisfy modern energy requirements.
As used herein, the term thermal break refers to a means which has a low thermal conductivity and thus serves as a heat barrier, or a break, in a heat path which serves to break or block the flow of heat through that heat path. The thermal conductivity of the heat break is thus low with respect to the rest of the heat path. Thus, a true thermal break is sufficiently non-conductive thermally to interrupt heat flow through the path which includes the thermal break and reduce that heat flow to levels acceptable to modern building requirements. It is noted that heat may flow, through nearly any non-theoretical, path, but the true thermal break reduces heat flow be negligible levels, whereas the devices of the prior art, while interrupting heat flow somewhat, are not true thermal breaks as heat flow through the heat path is not reduced to such negligible levels, but is only slightly reduced. Thus, the prior art devices had no true "break" in the heat path, merely a slight barrier. A true thermal break thus serves to (essentially) stop heat flow, as compared to a heat barrier which offers only some impediment thereto.